In general, a hydrogen-containing gas (a reformed gas) generated by reforming a hydrocarbon-based fuel (a reforming feedstock), such as kerosene and city gas, in a reformer is supplied to a solid oxide fuel cell (hereinafter sometimes called SOFC). Electric power is generated by causing this reformed gas and air to react electrochemically in the SOFC.
Usually, the SOFC is caused to operate at high temperatures of the order of 550° C. to 1000° C.
The steam reforming reaction used in reforming is a reaction involving very large endotherm, the reaction temperature is relatively high, and a high-temperature heat source is necessary. For this reason, there is known an indirect internal reforming SOFC in which a reformer is disposed in the vicinity of the SOFC (in a position where the reformer receives heat radiation from the SOFC) and the reformer is heated by the radiation heat from the SOFC. Also, there is known a practice by which an anode off-gas (a gas discharged from an anode of an SOFC) containing combustible components is burned and the reformer is heated by using this combustion heat as the heat source.
The indirect internal reforming SOFC is described in Patent Document 1.
Patent Document 1: Japanese Patent Laid-Open No. 2002-358997